Phasor Diagrams and Z-Plane Plots with Pikchr

I thought it might be nice to have some rectangular and polar graph paper for studying pole-zero plots by hand on the Z-plane, so I whipped this up in Pikchr:

(source code)

I was pleasantly surpised to learn that Pikchr supports macros. It's only documented in the language grammar, but it works well to simplify diagram source code and extend the little language.

And for when I want to make SVG files for phasor diagrams there's this:

(source code)

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